STING Signaling Drives Production of Innate Cytokines, Generation of CD8+ T Cells and Enhanced Protection Against Trypanosoma cruzi Infection

A variety of signaling pathways are involved in the induction of innate cytokines and CD8+ T cells, which are major players in protection against acute Trypanosoma cruzi infection. Previous data have demonstrated that a TBK-1/IRF3-dependent signaling pathway promotes IFN-β production in response to Trypanosoma cruzi, but the role for STING, a main interactor of these proteins, remained to be addressed. Here, we demonstrated that STING signaling is required for production of IFN-β, IL-6, and IL-12 in response to Trypanosoma cruzi infection and that STING absence negatively impacts activation of IRF-dependent pathways in response to the parasite. We reported no significant activation of IRF-dependent pathways and cytokine expression in RAW264.7 macrophages in response to heat-killed trypomastigotes. In addition, we showed that STING is essential for T. cruzi DNA-mediated induction of IFN-β, IL-6, and IL-12 gene expression in RAW264.7 macrophages. We demonstrated that STING-knockout mice have significantly higher parasitemia from days 5 to 8 of infection and higher heart parasitism at day 13 after infection. Although we observed similar heart inflammatory infiltrates at day 13 after infection, IFN-β, IL-12, CXCL9, IFN-γ, and perforin gene expression were lower in the absence of STING. We also showed an inverse correlation between parasite DNA and the expression of CXCL9, IFN-γ, and perforin genes in the hearts of infected animals at day 13 after infection. Finally, we reported that STING signaling is required for splenic IFN-β and IL-6 expression early after infection and that STING deficiency results in lower numbers of splenic parasite-specific IFN-γ and IFN-γ/perforin-producing CD8+ T cells, indicating a pivotal role for STING signaling in immunity to Trypanosoma cruzi.

Morphological signs of neurogenic inflammation in the heart of rats during aging

С помощью гистологических методов окраски толуидиновым синим, гематоксилином и эозином и иммуногистохимических реакций на белок PGP 9.5, тирозингидроксилазу (ТГ), белок Iba-1, изучены клеточные изменения в разных отделах сердца крыс линии Wistar в возрасте 18- 23 мес. В соединительной ткани основания сердца обнаружены очаговые воспалительные инфильтраты, внутри которых выявлены PGP 9.5 и ТГ сплетения, состоящие из парасимпатических и симпатических нервных волокон. В области клапанного аппарата, на границе фиброзного кольца и миокарда правого предсердия, обнаружены патологические изменения нервных структур - дегенерация нервных пучков и зернистый распад варикозных аксонов терминального сплетения. Установлены тесные взаимоотношения аксонов терминальной нервной сети с клетками воспалительных инфильтратов и кровеносными сосудами. Определены закономерности встречаемости в различных отделах миокарда у старых животных нейроклеточных воспалительных комплексов, состоящих из нервных волокон, кровеносных капилляров и клеток-участников местного воспалительного процесса (тучных клеток, макрофагов, фибробластов, плазмоцитов). Установлен хронический характер нейрогенного воспаления в сердце при старении. Using histological methods of staining with toluidine blue, hematoxylin-eosin and immunohistochemical reactions for the PGP 9,5 protein, tyrosine hydroxylase (TH), Iba-1 protein, cellular changes in different parts of the heart of Wistar rats at the age of 18-23 months were studied. In the connective tissue of the heart base, focal inflammatory infiltrates were found, near which PGP 9.5 and TH plexuses, consisting of parasympathetic and sympathetic nerve fibers, were detected. In the area of the valvular heart apparatus, at the border of the anneau fibreux and the myocardium of the right atrium, pathological changes in nerve structures were found: degeneration of nerve fibers and granular destruction varicose axons of the terminal plexus. A close relationship has been established between axons of the terminal nervous network and cells of inflammatory infiltrates and blood capillaries. The features of the localization of neurocellular inflammatory complexes consisting of nerve fibers, blood capillaries and cells participating in the local inflammatory process (mast cells, histiocytes, monocytes, fibroblasts, plasma cells) in various parts of the myocardium in old animals are described. The chronic nature of neurogenic inflammation in the heart during aging has been established.

The Colombian Strain of Trypanosoma cruzi Induces a Proinflammatory Profile, Neuronal Death, and Collagen Deposition in the Intestine of C57BL/6 Mice Both during the Acute and Early Chronic Phase

The objective of this study was to evaluate the histopathological changes caused by infection with the Colombian strain of Trypanosoma cruzi (T. cruzi) in the acute and chronic experimental phases. C57Bl/6 mice were infected with 1000 trypomastigote forms of the Colombian strain of T. cruzi. After 30 days (acute phase) and 90 days (early chronic phase) of infection, the animals were euthanized, and the colon was collected and divided into two parts: proximal and distal. The distal portion was used for histopathological analysis, whereas the proximal portion was used for quantification of pro- and anti-inflammatory cytokines. In addition, the weight of the animals and parasitemia were assessed. The infection induced gradual weight loss in the animals. In addition, the infection induced an increase in interferon gamma (IFNγ) and tumor necrosis factor-alpha (TNF-α) in the intestine in the acute phase, in which this increase continued until the early chronic phase. The same was observed in relation to the presence of intestinal inflammatory infiltrates. In relation to interleukin (IL)-10, there was an increase only in the early chronic phase. The Colombian strain infection was also able to induce neuronal loss in the myenteric plexus and deposition of the collagen fibers during the acute phase. The Colombian strain of T. cruzi is capable of causing histopathological changes in the intestine of infected mice, especially in inducing neuronal destructions. Thus, this strain can also be used to study the intestinal form of Chagas disease in experimental models.

Immunophenotype of the inflammatory response in the central and enteric nervous systems of cockatiels (Nymphicus hollandicus) experimentally infected with parrot bornavirus 2

Proventricular dilatation disease is a lethal disease of psittacine birds. In this study, we characterized the local cellular immune response in the brain, proventriculus, and small intestine of 27 cockatiels ( Nymphicus hollandicus) experimentally infected with parrot bornavirus 2 (PaBV-2). Perivascular cuffs in the brain were composed of CD3+ T-lymphocytes and Iba1+ macrophages/microglia in most cockatiels (n = 26). In the ganglia of the proventriculus, CD3+ T-lymphocytes (n = 17) and Iba1+ macrophages (n = 13) prevailed. The ganglia of the small intestine had a more homogeneous distribution of these leukocytes, including PAX5+ B-lymphocytes (n = 9), CD3+ T-lymphocytes (n = 8), and Iba1+ macrophages (n = 8). Our results indicate that perivascular cuffs in the brain and the inflammatory infiltrate in the proventriculus of PaBV-2-infected cockatiels is predominately composed of T-lymphocytes, while the inflammatory infiltrates in the ganglia of the small intestine are characterized by a mixed infiltrate composed of T-lymphocytes, B-lymphocytes, and macrophages.

Bagaza virus and Plasmodium spp. coinfection in red-legged partridges ( Alectoris rufa ), in southern Spain 2019

Flaviviruses West Nile (WNV), Usutu (USUV) and Bagaza (BAGV) virus and avian malaria parasites are vector borne pathogens that circulate naturally between avian and mosquito hosts. WNV and USUV and potentially also BAGV constitute zoonoses. Temporal and spatial co-circulation and co-infection with Plasmodium spp., and West Nile virus has been documented in birds and mosquito vectors, and fatally USUV infected passerines coinfected with Plasmodium spp. had more severe lesions. Also, WNV, USUV and BAGV have been found to co-circulate. Yet little is known about the interaction of BAGV and malaria parasites during consecutive or co-infections of avian hosts. Here we report mortality of free-living red-legged partridges in a hunting estate in Southern Spain due to coinfection with BAGV and Plasmodium spp. The outbreak occurred in the area where BAGV first emerged in Europe in 2010 and where co-circulation of BAGV, USUV and WNV was confirmed in 2011 and 2013. Partridges were found dead in early October 2019. Birds had mottled locally pale pectoral muscles, enlarged, congestive greenish-black tinged livers and enlarged kidneys. Microscopically congestion and predominantly mononuclear inflammatory infiltrates were evident and Plasmodium phanerozoites were present in the liver, spleen, kidneys, muscle and skin. Molecular testing and sequencing detected Plasmodium spp. and BAGV in different tissues of the partridges, and immunohistochemistry confirmed the presence and co-localization of both pathogens in the liver and spleen. Although Plasmodium spp. are known to be highly prevalent in red-legged partridges, this is the first account of mortality caused by co-infection with BAGV and Plasmodium sp. Due to the importance of the red-legged partridge in the ecosystem of the Iberian Peninsula and as driver of regional economy such mortalities are of concern. Also, they may reflect climate change related changes in host, vector and pathogen ecology and interactions that could emerge similarly in other pathogens.

Siponimod Inhibits the Formation of Meningeal Ectopic Lymphoid Tissue in Experimental Autoimmune Encephalomyelitis

Background and ObjectivesTo investigate whether the formation or retention of meningeal ectopic lymphoid tissue (mELT) can be inhibited by the sphingosine 1-phosphate receptor 1,5 modulator siponimod (BAF312) in a murine model of multiple sclerosis (MS).MethodsA murine spontaneous chronic experimental autoimmune encephalomyelitis (EAE) model, featuring meningeal inflammatory infiltrates resembling those in MS, was used. To prevent or treat EAE, siponimod was administered daily starting either before EAE onset or at peak of disease. The extent and cellular composition of mELT, the spinal cord parenchyma, and the spleen was assessed by histology and immunohistochemistry.ResultsSiponimod, when applied before disease onset, ameliorated EAE. This effect was also present, although less prominent, when treatment started at peak of disease. Treatment with siponimod resulted in a strong reduction of the extent of mELT in both treatment paradigms. Both B and T cells were diminished in the meningeal compartment.DiscussionBeneficial effects on the disease course correlated with a reduction in mELT, suggesting that inhibition of mELT may be an additional mechanism of action of siponimod in the treatment of EAE. Further studies are needed to establish causality and confirm this observation in MS.

Guillain-Barre syndrome related to COVID-19: muscle and nerve biopsy findings

Background: The involvement of the peripheral nervous system (PNS) in COVID-19 is rare and, to date, morphological aspects from muscle and nerve biopsies have not been reported. Here, we describe a case of Guillain-Barré Syndrome (GBS) related to COVID-19 and demonstrate findings from peripheral nerve and skeletal muscle biopsies. A 79-year-old man presented with progressive weakness in both legs over one-week, evolving to both arms and urinary retention within 6 days. Four days earlier, he had a cough, febrile sensation and mild respiratory discomfort. On admission, his was afebrile, and without respiratory distress. A neurological examination disclosed asymmetric proximal weakness, diminished reflexes and no sensitive abnormalities. Three days later, the patient presented with bilateral facial weakness and proximal muscle strength worsened. Deep tendon reflexes and plantar responses were absent. Both superficial and profound sensitivity were decreased. From this point, oxygen saturation worsened, and the patient was placed on mechanical ventilation. CSF testing revealed one cell and protein 185 mg/dl. A chest CT showed the presence of ground-glass opacities and RT-PCR for SARS-CoV-2 was positive. The muscle biopsy revealed moderate neuromyopathic findings with positive expression for MHC-class I, C5b9, CD8 and CD68. The nerve biopsy showed inflammatory infiltrates predominantly with endoneurial compound formed by CD45 and CD68. The patient was treated with Oseltamivir for 9 days followed by IVIG for 5 days and died three days later of septic shock. Discussion: This is the first documented case of GBS associated with COVID-19 with a muscle and nerve anatomopathological study. A systematic review about neurological complications caused by COVID-19 described 11 patients with GBS. The morphological features reported in our patient showed signs of involvement of the immune system, suggesting that direct viral invasion could have played a role in the pathogenesis of peripheral nerve injury. Hereafter, further research will be necessary to understand the triggers for these cells migrating into the peripheral nerve.

A Case of Langerhans Cell Histiocytosis involving the External Auditory Canal

Langerhans cell histiocytosis (LCH) is commonly characterized by abnormal function and differentiation or proliferation of monocytes. In LCH, granulomatous lesions, including langerine-positive histocytes and inflammatory infiltrates, can occur to all tissues, particularly well in the bones, skin, lungs, and pituitary gland. In case of external auditory canal LCH, conductive hearing loss may occur, and the most common symptom is otorrhea. Here we present a case that 49-year-old male with external auditory canal mass. Since no invasive findings were seen in radiologic study, endoscopic transcanal excision was performed and LCH was proven by pathologic report. We present this case of external auditory canal LCH with the review of literature.

Pathological Features of COVID-19 Pneumonia Diagnosed Following an Autopsy

After initial emergence at the end of 2019, coronavirus disease 19 (COVID-19) rapidly spread to become a pandemic. The causative agent is recognized as a novel coronavirus, named as severe acute respiratory syndrome coronavirus 2, which is known to primarily affect the respiratory system. We present the case of a 60-year-old man who was diagnosed to have COVID-19 pneumonia following an autopsy. Microscopic examination of the lung tissue showed acute (exudative) phase of diffuse alveolar damage, inflammatory infiltrates in alveolar spaces and interstitium, atypical pneumocytes with prominent nucleoli and expanded cytoplasm, and thrombi in small arterioles. Some megakaryocytes were observed, which were positive for immunohistochemical stain for CD61. The pathological findings observed in this case were consistent with those of previously published reports of COVID-19 pneumonia. This is the first case of COVID-19 pneumonia diagnosed with an autopsy in Korea.